NEW YORK — One door closes; another door, well, closes. And that appears to be good news for Teva. Recent news that the Food and Drug Administration has rejected the drug maker's application for a new indication for multiple sclerosis drug Copaxone likely will mean the agency will not be so quick to approve a generic version of the drug without requiring a generic company to perform full clinical trials.

In its response to Teva, the FDA noted that it could not approve the application for a lower-dose from of Copaxone as the drug’s mechanism was not fully understood. "Unless you can provide a convincing argument that the new higher concentration/lower volume formulation does not have an impact on efficacy, an adequate and well-controlled efficacy study will be needed to support efficacy of this new formulation," the FDA noted.

“This response supports Teva's belief that even slight changes to a glatiramoid like Copaxone can significantly and unpredictably influence the efficacy, toxicity and immunogenicity profile of the compound,” the company noted.